1. Viruses, Bacteria, Fungi
Diversity of Life
Vocab
Important Info
Headings

2. VIRUSES Viruses are non-living organisms.
Technically they are not considered living organisms, since they cannot self replicate (they’re not a kingdom)
Remember that living organisms:
Are highly organized
Stable chemical composition
Take energy & use it
Respond to stimuli
Grow & develop
Able to self reproduce (sexually or asexually)
Show genetic variation
Adapt to their environments

3. Virus structure
Viruses: Just a protein coat for protection (capsid) and a nucleic acid (RNA or DNA) for information on how to make more copies of the same virus
Cannot replicate/reproduce on its own! Needs a host…

4. Virus is a cellular parasite
Uses cell machinery of a host cell to replicate and to produce more viruses
They come in many varieties, sizes & shapes

5. Viruses cause diseases
Viruses cause numerous diseases in Plants, animals, bacteria & fungi…
Examples of human viruses:
Herpes virus
Hepatitis virus
Rabies
Ebola – emerging epidemics
Influenza (“flu”) – respiratory infection (fever, headache, chills, cough, stuffy nose, sore throat) caused by a variety of viruses. Flu season: Nov. – March.
Passed on by sneezing, coughing – air, hand-to-mouth, etc.
Vaccine helps prevent outbreaks.

6. Human Viruses Human Immunodeficiency Virus (HIV) – causes AIDS.
Transmitted through sexual contact, sharing infected needles, blood transfusions, mother to baby.
Severe Acute Respiratory Syndrome (SARS) – brand new deadly virus, started in China, causes atypical pneumonia. Spreads quickly.

7. Plant Viruses Tobacco Mosaic Virus (TMV) causes mottling symptoms
Rose mosaic virus
Spots on fruit
Wheat stunt virus

8. Kingdoms Living organisms are divided into kingdoms…
Kingdom Division Class Order Family Genus Species
Taxonomic hierarchy for classifying organisms
Scientific name = Genus + Species

9. Five Kingdoms Living organisms are classified in five kingdoms:
Monera: bacteria, originally classified as plants because they have cell walls
Protista: algae, slime molds, protozoa (have a cell wall, not cellulose)
Fungi: mold, mildew, mushrooms. In past were class. as plants because they have cell walls and are ‘rooted’ in ground
Plantae: Complex multicellular eukaryotes, obtain nutrients by photosynthesis
Animalia: Complex multicellular eukaryotes, obtain food by ingestion

10. Living organisms PROKARYOTIC – Lack membrane-bound organelles
Kingdom Monera
EUKARYOTIC – have membrane bound organelles.
Kingdoms Protista, Plantae, Fungi, Animalia

11. PROKARYOTES Bacteria are small and unicellular
They have no internal organelles (no chloroplasts, nucleus, ER, mitochondria)
Haploid (n) only

12. Bacteria
Replication is asexual – clonal, rapid simple division (no mitosis)
Pseudo-sexual reproduction, has means for Genetic exchange
Called conjugation

13. Bacteria Bacterial forms: cocci, bacilli, spirilli
Some forms are photosynthetic: cyanobacteria

14. Bacterial pathogens Animal pathogens: Typhoid, tuberculosis
Bubonic plague or “Black Death”, transmitted by fleas (caused 25 million deaths in Medieval Europe)
Syphilis, gonorrea (venereal diseases)
E. coli, Salmonella (food poisoning) 76 million illnesses worldwide

15. Bacterial control There are ways of controlling bacterial growth:
Disinfectants
Antibiotics
Low temperatures
High temperatures,
Low oxygen

16. Beneficial Bacteria
Nitrogen-fixation – convert atmospheric N into useful Nitrogen (N gas  plants  animals)
Decomposition in the biosphere – get rid of dead organisms, nature’s recyclers
Intestinal Bacteria – supply vitamins (K)
Commercial use: yogurt, sour cream, fermentation
Genetically-engineered bacteria produce insulin and other important chemicals.
Can also help clean up oil spills: oil ‘eating’ bacteria!

17. Eukaryotes Four Kingdoms: Fungi, Protista, Plantae, Animalia
Have organelles (nucleus, mitochondria, etc.)
Arose from endosymbiosis
Endosymbiont Theory

18. Endosymbiont Theory
Looking at the differences between prokaryotes and eukaryotes…
How did eukaryotic organisms evolve?
How did chloroplasts and mitochondria evolve?
Chloroplasts and mitochondria:
Same size as bacteria
Have their own DNA
Divide similarly

19. Endosymbiont Theory
Chloroplasts and Mitochondria are descendants of once free-living prokaryotes that were engulfed by larger cells…
establishing a symbiotic (mutually beneficial) relationship.

20. Kingdom Fungi Characteristics of fungi: Eukaryotic
Non-photosynthetic, must obtain nutrients by absorption (produce digestive enzymes)
Have a cell wall! Fungi cell wall is made of chitin and/or cellulose
Occur in haploid (n) and diploid (2n) stages
Reproduce sexually and asexually

21. Fungal morphology
Most fungi come in thread-like strands, called hyphae (collectively called mycelium)
Other fungi are single-celled, called yeasts.
Form spores that can spread by wind, air or soil (give us allergies!)
Fungi are so successful because they can reproduce both sexually and asexually
Sexual spores – (by meiosis) mushroom is spore-producing structure, formed by many hyphae
Asexual spores (by mitosis)

22. Fungi Hyphae: filaments

23. Fungal structure and reproduction
Club fungi (mushrooms): Genetically compatible fungi fuse, combining cytoplasm and nuclei
Nuclei in the same cell do not fuse, producing a heterokaryotic (n+n) hyphae – which in turn forms the fruiting body (mushroom)
Underneath the cap, in the gills, n+n cells are called basidia
Nuclei combine, form a zygote which undergoes meiosis and produces haploid spores of diverse genotypes for dispersal.
See animation

24. Fungal fruiting bodies
Coalescence of many hyphae. Role of spore production. Mushrooms
Have cap and stalk. Spores are produced in the gills, under the cap.

25. Significance of Fungi Many fungi are beneficial
As decomposers: fungi obtain nutrition from organic matter, so they recycle nutrients

26. Mycorrhizae
Mycorrhizae (“fungus roots”) -- certain fungi grow into roots of most plants to supply water, P and N.
90% of plants need mycorrhyzae to survive
An example of coevolution: symbiotic relationship. Fungus gets sugars from plants, and fungus provides P and water to plant

27. Fungi act as antibiotics
Penicillin is produced by species of the fungus Penicillium, which kills bacteria.
Discovered by Alexander Fleming in 1928.
He left some unwashed plates with bacteria, went on vacation, and saw that a mold was growing, inhibiting the growth of the bacterial colony (Nobel Prize 1945).

28. Pathogenic fungi
Pathogenic fungi grow within a host, using the host as food for replication
Human Diseases:
Athlete’s foot
Yeast infections
Ring worm
Candidiasis

29. Pathogenic fungi: Mycotoxins
Mycotoxins are harmful, toxic chemicals produced by fungi and which accumulate in infected food
Aflatoxins contaminate corn and peanuts.
The Aspergillus fungi grows on corn/peanuts and makes one of the most potent carcinogens known (aflatoxins)

30. Pathogenic fungi: Mycotoxins
Ergot of rye – a fungus that infects the flowers of the rye plant.
Produces fungal structures on the seed head, which are harvested with the rye seed  bread
Eating the Ergot-infected rye produces poisoning bye the compounds produced by the fungus (Ergotism or St. Anthony’s Fire)
Causes nervous spasms, convulsions, delirium, tingling, gangrene. (40K deaths in yr. 944)

31. Plant Diseases caused by fungi
Fungus can infect plants also
Examples of fungal plant pathogens:
Lawn diseases
Apple scab
Fire blight

32. Fungal plant pathogens
Epidemics: Dutch Elm disease
Wiped out American elms in U.S.

33. Irish potato famine
Irish Potato Famine (1845) 1 million deaths, massive migration
Caused by potato blight fungus Phytophthora infestans

34. Commercial uses of fungi
Yeast for fermentation. Yeast breaks down sugars to produce ethyl alcohol and CO2
Brewing of alcoholic beverages: beer, wine – yeast turns sugars of grains, grapes into alcohol and carbon dioxide (bubbles)

35. Commercial uses of fungi
Bread making – carbon dioxide bubbles help dough rise

36. Commercial uses of fungi
Cheese production – blue cheeses such as
Roquefort
Stilton
Camembert

37. Commercial uses of fungi
Edible fungi are the sexual structures of fungi, the mycelium remains
Mushrooms
Morels
Truffles

38. Edible fungi
Corn smut – a parasite of corn, is actually eaten in Mexico, a delicacy (huitlacoche)

39. Other types of fungus Poisonous – some very dangerous intoxicants
Hallucinogenic fungi